Body Systems & Homeostasis Flashcards
stem cell
undifferentiated/unspecialized cells which can self-renew and develop into various cell types
cell differentiation
stem cells specialize and become specialized cells
gene expression
process where specific genes are expressed which dictates how a cell differentiates and functions
cell potency
a cell’s ability to differentiate into other cell types
totipotent
capable of differentiating into any cell type (e.g. zygote)
pluripotent
capable of differentiating into three germ layers (e.g. embryonic stem cell)
multipotent
capable of differentiating into limited cell types (e.g. adult stem cell)
unipotent
capable of differentiating into one cell type (e.g. somatic cell)
hierarchy of multicellular organisms
specialized cell → tissue → organ → system → organism
homeostasis
process where organisms maintain stable internal environments to maintain an optimal range for metabolism
negative feedback
homeostatic mechanism which employs receptors and effectors to achieve equilibrium and balance by reversing the direction of the stimulus
receptors
sensors which detect changes in both internal and external environments
thermoreceptor
temperature stimulus (e.g. skin)
chemoreceptor
specific chemical compounds stimuli (e.g. taste bud)
photoreceptor
light stimulus (e.g. eye)
mechanoreceptor
touch & pressure stimuli (e.g. skin)
nociceptor
pain stimulus (e.g. skin)
electroreceptor
electricity stimulus (e.g. skin)
osmoreceptor
osmotic pressure stimulus (e.g. hypothalamus)
baroreceptor
blood pressure stimulus (e.g. blood vessel)
effectors
muscles or glands which respond to receptors to correct imbalance
homeostasis in the body
nervous (electrical impulses) & endocrine (hormones) systems
small sa:v ratio
structural - mitigates heat loss through diffusion
fat/blubber
structural - traps heat through insulation
large vascularized ears
structural - augments heat loss through a large surface area & many blood vessels
brown adipose tissue
structural - generates heat by converting stored fat
mitochondrial activity
structural - generates heat by producing energy (ATP)
vasodilation
physiological - expands blood vessels to increase heat loss to surroundings
vasoconstriction
physiological - shrinks blood vessels to decrease heat loss to surroundings
shivering
physiological - rapid contractions of skeletal muscles to generate heat
piloerection
physiological - creates layers of air that insulate the body
counter-current exchange
physiological - minimizing the heat gradient against surroundings
kleptothermy
behavioural - sharing or stealing another organism’s body heat
torpor
behavioural - physiological process of lowering body temperature and metabolic rate to conserve energy
hibernation
prolonged torpor which occurs during winter for endotherms (e.g. mammals)
brumation
prolonged torpor which occurs during winter for ectotherms (e.g. reptiles)
aestivation
prolonged torpor which occurs during summer for ectotherms (e.g. lungfish)
gas exchange medium characteristics
moist; vascularized; thin; large surface area
counter-current exchange in fish
maximises oxygen intake through maintaining a concentration gradient
water runs in the opposite direction to the blood flow
obligate air breather
fish that have poorly developed gills and are obliged to breathe air
facultative air breather
fish that have well-developed gills and are not reliant to breathe air
mammalian lung ventilation
ribs, intercostal muscles and diaphragm create negative pressure
air flows from the trachea > bronchus > bronchiole > alveoli
frog lung ventilation
two-phase inhalation
buccal cavity > lungs
oxygen dissociation curve (higher temperature)
right shift; haemoglobin has a lower affinity for oxygen, oxygen is more readily available
oxygen dissociation curve (higher carbon dioxide)
right shift; haemoglobin has a lower affinity for oxygen, oxygen is more readily available
oxygen dissociation curve (higher acidity / lower pH)
right shift; haemoglobin has a lower affinity for oxygen, oxygen is more readily available
oxygen dissociation curve (smaller animal size)
right shift; haemoglobin has a lower affinity for oxygen, oxygen is more readily available
oxygen dissociation curve (low oxygen)
left shift; haemoglobin has a higher affinity for oxygen, oxygen is less readily available
carbohydrates (monomer / digestive enzyme)
monosaccharides / amylase
proteins (monomer / digestive enzyme)
amino acids / protease
lipids (monomer / digestive enzyme)
fatty acids / lipase
nucleic acid (monomer)
nucleotides
foregut fermenters (ruminants)
cellulose digestion occurs in the rumen (e.g. cows)
hindgut fermenters (non-ruminants)
cellulose digestion occurs in the caecum (e.g. rabbits)
ammonia
high toxicity
no ATP required to produce
highly soluble
high quantity of water required for excretion
e.g. aquatic animals
urea
medium toxicity
3 ATP required to produce
moderately soluble
moderate quantity of water required for excretion
e.g. mammals
uric acid
low toxicity
7 ATP required to produce
barely soluble
low quantity of water required for excretion
e.g. reptiles
glomerulus
filtration of blood
bowman’s capsule
filtration of blood
proximal convoluted tubule
re-absorption of glucose & ions
loop of henle
re-absorption of water & salt
generation of a concentration gradient to produce urine
distal convoluted tubule
secretion to regulate pH
collecting tubule
collection of urine
endotherm
constant body temperature independent from the ambient temperature
heat generated from an internal source
(e.g. mammals)
ectotherm
changing body temperature dependent on the ambient temperature
heat generated from an external source
(e.g. reptiles)
osmoregulator
constant internal osmotic environment independent from the external osmotic environment
osmotic gradient
(e.g. humans)
osmoconformer
changing internal osmotic environment dependent on the external osmotic environment
isotonic
(e.g. lobsters)
